The purpose of this proposal is to study changes which take place in the microcirculation of neonate cardiac, pulmonary and cerebral cortex tissue which is transplanted into the cheek pouch chamber of an adult hamster when hypertension is induced in the latter as well as when the hypertension is reversed. The microcirculation will be characterized by measuring vessel reactivity, wall and lumen size, hydrostatic pressure profiles and vascular permeability.